ES2748232T3 - Oil pump mounting arrangement on a refrigeration compressor - Google Patents

Abstract

Refrigeration compressor, comprising an oil pump assembly, comprising a casing (10) inside which is arranged an electric motor (20), including a stator (30), carrying a plurality of coils ( 31) spaced circumferentially from each other, and a rotor (40), associated with a drive shaft (50) and a pin (51) arranged internally and concentrically with respect to said drive shaft (50); the drive shaft (50) collaborating with the pin (51) to define helical channels (52) that delimit the path (60) of the lubricating oil, when it is pumped due to the relative revolution between the drive shaft (50) and the pin (51); and a clamping rod (70), capable of anchoring said pin (51) in a fixed part (80) of the electric motor (20); wherein said clamping rod (70) is supported, in the middle part thereof, on the pin (51) and, at the ends thereof (71), on respective seats (81) defined in the fixed part (80) from the electric motor (20); said compressor being characterized by the fact that: the clamping rod (70) extends through free spaces (33) arranged in the fixed part (80) of the electric motor (20), longitudinally aligned with spaces (34 ) defined between adjacent coils (31); and the ends (71) of the clamping rod (70) are housed in the seats (81) on the inner sides (82) thereof.

Description

DESCRIPTION

Oil pump mounting arrangement on a refrigeration compressor

Technical field of the invention

The present application relates to an oil pump mounting arrangement for refrigeration compressors. The purpose of an invention of this type is to provide said compressor with a better use of the interior space defined by the body thereof, to allow its miniaturization.

State of the prior art

According to the general knowledge available in the state of the art, most of the refrigeration compressors comprise an external wrapping body that surrounds various functional components, such as a compression mechanism basically consisting of a piston / cylinder assembly, being displaced the piston by a connecting rod that is connected to an eccentric shaft that is defined and extends from a drive shaft that rotates together with the rotor of an electric motor, as well as the electric motor itself, basically defined by said rotor and a stator.

It is known that an essential aspect for the proper functioning of these compressors consists in the lubrication of the moving parts (piston, connecting rod, eccentric shaft, etc.) and / or the surfaces with which they collaborate. This lubrication is normally provided by pumping lubricating oil provided in the oil tank (sump) defined inside the casing, in the lower part thereof. This oil is pumped to get to the right components and then returns to the crankcase by gravity.

It is also known, in the state of the art, that these oil pumps (centrifugal or helical) are formed by the compressor drive shaft itself or coupled to it, at the lower end thereof, and partially submerged in the oil lubricant contained in the tank. Additionally, it is quite normal for drive shafts to comprise grooves on the outer surface thereof, capable of aiding in pumping oil to the other moving components of the compressor.

More specifically, the oil pumps of some models of current refrigeration compressors comprise a helical pump, formed by the interaction between a stationary pin and a hollow bottom part integrated or coupled to said drive shaft of the compressor's electric motor, provided by the concentric and slightly loose fitting thereof, a helical groove being arranged in at least one of these. Quite didactic examples of this constructive spirit are highlighted in Patent Documents BRP19201761, WO2005 / 047699, US6450785 and WO96 / 29516.

This type of pump allows a large flow of oil to be raised, even when the compressor operates at low revolutions, which is especially desirable when the refrigeration compressor is of the variable speed type.

In order to provide support to the pin, there are several known arrangements that use tie rods, with a format substantially similar to a "U", that pass over said pin at one of its ends and anchor them next to a fixed part of the block. cylinder or electric motor, such as the stator, or a protective cover attached at the bottom to said stator.

Such tie rods are easily identified in US6450785, JP20055337158 and BRPI0804302, as well as in WO2005 / 047699 and WO96 / 29516.

However, all of these documents have a common drawback, namely said "U" -like format of the clamping rods. Due to this geometric configuration, such tie rods tend to take up too much space inside the housing.

Specifically, the clamping rod disclosed by Patent Document BRPI0804302 is arranged in such a way that it avoids the protective cover of the motor and / or the heads of its electric coils, with its ends housed in substantially horizontal seats in order to define a geometric, perpendicular and coplanar pivot shaft with respect to the rotor rotation shaft.

As a disadvantageous consequence of these types of prior art arrangements (rod with a format similar to a "U"), the possibility of the clamping rod colliding with the compressor housing body, especially during transport or during starts, is mentioned. (on) and stops (off) the compressor. The incidence of these collisions is even greater when the distance between this clamping rod and the casing body is reduced, which tends to happen due to the constant and current miniaturization of the refrigeration compressors.

In an even more critical situation, considering the different compressor models, it is possible that this distance is so small that it even prevents this type of solution.

Furthermore, the "exposure" of such clamping rods, given their curvature, can lead to a greater probability of mounting errors, arising from possible collisions of said clamping rod against mounting devices or other internal components of the compressor during the mechanical process of introducing the kit inside said casing. Such a problem seems to be even more critical in the case of the arrangement described by Patent Document BRPI0804302, because the contour of the rod is arranged around the protective cover of the motor and / or the head of the coils.

In this regard, Patent Document EP1605163 already discloses a mounting arrangement for pin holding rods of the helical pump, in which said rod comprises a format similar to two consecutive "S" curves, in each of the right and left sides of the pump pin (see Figures 1 and / or 3 of this document), mounted in such a way that they do not protrude from the circumference (the vertical projection) of the stator. It should be noted that some of the clamping rods of the aforementioned documents do not protrude from the circumference of the stator, regardless of their format.

Thus, despite the fact that some helical oil pump mounting arrangements in refrigeration compressors have proven to be somewhat functional to this day, it can be seen that all of them lack simple constructive solutions that can optimize the space occupied by the clamping rod inside the compressor's wrapping body, guaranteeing an adequate assembly of the assembly and the protective operation of the electric motor and, at the same time, that they consist of an easy and economic manufacturing solution, also maintaining the concept defined in patent document BRPI0804302, in which the clamping rod has a part attached to one of the parts of the cylinder block and the stator, according to a geometric pivot shaft, perpendicular to the geometric shaft of the rotor rotation and coplanar with regarding it.

Objectives of the invention

Therefore, in view of all of the above, the main objective of the present application is to disclose an oil pump mounting arrangement in a refrigeration compressor capable of providing the compressor with better utilization of the interior space defined by the body surrounding it, in order to allow its miniaturization.

It is also an objective of the present application that the arrangement of the mounting of the oil pump in a refrigeration compressor allows a good precision in the construction of the same, an easy and reliable assembly and an easy and economic manufacture, guaranteeing the adequate lubrication. of compressor parts, even at low rotational speed.

Furthermore, an objective of the present application is for the arrangement of the oil pump assembly in a refrigeration compressor to precisely define, in its anchorage, a geometric pivot shaft, perpendicular to the rotor rotation geometric shaft and coplanar with regarding it.

Features of the invention

Thus, in order to achieve the objectives and technical effects indicated above, the present application refers to an oil pump mounting arrangement in a refrigeration compressor, which comprises a housing inside which is arranged an electric motor including a stator carrying a plurality of circumferentially separated coils and a rotor connected to a drive shaft and an inner pin arranged concentrically with respect to said drive shaft, in which the drive shaft cooperates with the pin to define helical channels that delimit the path of the lubricating oil when it is pumped due to the relative revolution between said drive shaft and the pin. Also, a clamping rod capable of anchoring said pin is arranged in a fixed part of the electric motor.

According to the present invention, said clamping rod rests, in the middle part thereof, on the pin and, at the ends thereof, on the respective seats defined in the fixed part of the electric motor, in which said rod Clamping extends through longitudinally aligned clearances with defined gaps between adjacent coils. The ends of the tie rod are housed in seats on the inside sides of the tie rod.

Preferably, the seats are defined by protrusions, diametrically opposed to each other, which extend radially outwardly from an outer surface of a protective cover of the electric motor. The protective cover is polymeric and is made by injection molding, and the protrusions are formed from at least two adjacent and opposite halves.

Even preferably, the length of the clamping rod is completely arranged inside the circumference defined by the protective cover and its projections.

Brief description of the drawings

The characteristics, advantages and technical effects of the present application, as described above, will be better understood by a person skilled in the art, from the following detailed description, made by way of example, and not as a limitation, of embodiments of the invention, and referring to the attached schematic figures, that:

Figure 1 shows a schematic front sectional view of a refrigeration compressor according to the prior art.

Figure 2 shows a schematic front sectional view of a refrigeration compressor according to the preferred embodiment of the present invention.

Figure 3 shows, in detail, the oil pump pin mounted on the tie rod.

Figure 4 shows a bottom view of the refrigeration compressor oil pump assembly arrangement near the stator of the electric motor, according to the present invention.

Figure 5 shows a front view of the oil pump mounting arrangement of a refrigeration compressor in the protective cover, according to the preferred embodiment of the invention.

Figure 6 shows a detailed enlarged view of the seats defining the end housing of the oil pump pin retaining rod, according to the preferred embodiment of the mounting arrangement of the present invention.

Detailed description of the invention

According to the schematic figures mentioned above, some examples of possible embodiments of the arrangement of the mounting of the oil pump in the refrigeration compressor, object of the present invention, will be described in more detail below, but simply by way of illustration, not limitation. . This is because the present invention can comprise different details and technical, constructive, structural and dimensional aspects, without affecting the present scope of protection.

Thus, as shown, the arrangement of the oil pump assembly in the refrigeration compressor is preferably applied to small-speed, variable-speed compressors, in which this type of compressor comprises a casing 10 in the interior of which is arranged an electric motor 20 that includes a stator 30, which carries a plurality of coils 31 circumferentially separated from each other and a rotor 40 associated with a drive shaft 50 and a pin 51 arranged internally and concentric with respect to to said drive shaft 50.

The drive shaft 50 collaborates with the pin 51, to define helical channels 52 that delimit the path of the lubricating oil when it is pumped due to the relative revolution between the drive shaft 50 and the pin 51. Such helical channels 52 are defined due to the provision of grooves arranged on the inner surface of the underside of the drive shaft 50 or on the outer surface of the pin 51.

In order to anchor said pin 51 in a fixed part 80 of electric motor 20, a clamping rod 70 is provided, in which said clamping rod 70 is supported, in the middle part thereof, in a hole 53 arranged following the pin 51 and, at its ends 71, in the respective seats 81 defined in the fixed part 80 of the electric motor 20, said ends 71 being aligned with the geometric shaft defined by said seats 81.

Such hole 53 may be a through hole with respect to pin 51 itself or, preferably, may be defined by a handle 54 extending from the end of pin 51.

It should be noted that the coils 31, as is common knowledge to those skilled in the art, may be wound in housing parts 32 circumferentially spaced from each other, defined in the metal frame that forms the core of the stator 30 .

Thus, it is worth noting that between the coils 31 adjacent to each other there are defined spaces 34 in which the free spaces 33 are longitudinally aligned, as shown in Figure 4.

In this case, it is worth noting that the longitudinal direction refers to the main direction of the drive shaft 50 and, furthermore, that the free spaces 33 may be contained in the spaces 34 themselves, depending on the size of the coils 31.

Specifically, in accordance with the present invention, the tie rod 70 of the pin 51 extends through the coils 31, passing over the clearances 33 to allow the ends 71 of the tie rod 70 to be accommodated in the seats 81 by introducing it through the inner sides 82 of these seats 81. In other words, the ends 71 of the clamping rod 70 extend radially inward, protruding towards the housing body in the seats 81 .

These two characteristics, related to the arrangement of the clamping rod 70, that is, the length of the clamping rod 70 through the free spaces 33 and with their ends 71 introduced by the inner sides of the seats 81, are shown different from the state of the art and have technical advantages, since they allow optimizing the spatial arrangement of the internal components to the compressor casing, guaranteeing the minimum electrical distances required by the rules, since the clamping rod 70 does not need to avoid the extreme bottom of protective cover 90.

Even more preferably, the fixing part 80 of the electric motor 20 specifically refers to a protective cover 90, in which the seats 81 are defined by the projections 92, diametrically opposed to each other, which extend radially outwards from a outer surface 91 of this protective cover 90.

Consequently, it is essential that the length of the clamping rod 70 is fully disposed within the circumference (or vertical projection of the contour) defined by the protective cover 90 and its protrusions 92, so as to reduce the " Exposure ”of the tie rod 70.

More specifically, it is highly desirable that the ends 71 of the clamping rod 70 do not extend beyond the projections 92, to avoid eventual contact of these ends 71 with the casing 10 of the compressor or with any other element during the process For mounting, such contact could "push" the clamping rod 70 radially inward and cause these ends 71 of the seats 81 to disengage / disengage. Therefore, the clamping rod 70 has a curvilinear geometry, in which each of the halves of it resembles the letter "S". Therefore, a minor protrusion / "exposure" of the clamping rod 70 towards / with respect to the envelope body 10 of the compressor is clearly observed, allowing the electric motor 20 to be brought closer to the latter.

In this concrete construction, even if an eventual contact / collision of the pin 51 with the lower part of the compressor casing 10 occurs, either during its operation or during its assembly, the ends 71 of the clamping rod 70 will be driven in the radial direction from the inside to the outside, in such a way that they are inserted further into the seats 81, minimizing any risk of disengagement, unlike what happens in the prior art solutions, in which the ends 71 of the clamping rod 70 are housed in the seats 81 since their introduction by the outer sides thereof, such as in the object of patent document BRPI0804302.

The protective cover 90, also widely known to those skilled in the art, is polymeric and is made by injection molding due to the inherent advantages of this process over dimensional accuracy and cost.

Optionally, the specific supports for these seats 81 can be coupled to the stator 30 of the electric motor 20, with the same functionalities described above.

When considering a polymer injection process for the manufacture of said protective cover 90, and in such a way that the seats 81 are defined by the projections 92 as proposed by the invention, the use of mobile drawers in the injection mold is generally necessary .

Taking into account that the use of these drawers substantially increases the final price of the product, and in order to eliminate this problem, it is preferred that the projections 92 are formed from at least two adjacent and opposite halves, with respect to to the concavity of them.

This set of halves makes it possible to precisely define, up to the seats 81, a longitudinal geometric shaft that has a diameter equivalent to that of a continuous tubular hole.

In this way, and according to one of the objectives of this invention, a fixed part 80 (protective cover 90) that is easy to manufacture and low cost is achieved, which, however, guarantees the existence of a well-defined geometric pivot shaft, up to clamping rod 70, perpendicular and coplanar with respect to the rotation shaft of the rotor.

In view of the above, it is observed that the proposed invention now discloses a solution that provides a better use of the interior space defined by the body thereof, to allow its miniaturization, as well as easy and reliable assembly and manufacture easy and economic, guaranteeing, in addition, the adequate lubrication of the mobile components of the compressor, even when it works at low revolutions.

Finally, it is important to note that the present description has the sole purpose of describing, by way of example only, an embodiment of the arrangement of the oil pump assembly in a refrigeration compressor, according to the present invention. Therefore, it should be apparent to those skilled in the art that various constructive modifications, variations, and combinations of elements that perform the same function are substantially equal to achieve the same results, which are within the scope of protection defined by the appended claims.

Claims (5)

1. Refrigeration compressor, comprising an oil pump assembly, comprising a casing body (10) inside which an electric motor (20) is arranged, including a stator (30), which carries a plurality of coils (31) circumferentially spaced from each other, and a rotor (40) associated with a drive shaft (50) and a pin (51) arranged internally and concentric with respect to said drive shaft (50); the drive shaft (50) collaborating with the pin (51) to define helical channels (52) that delimit the path (60) of the lubricating oil, when it is pumped due to the relative revolution between the drive shaft (50) and the pin (51); Y a clamping rod (70), capable of anchoring said pin (51) in a fixed part (80) of the electric motor (20); in which said clamping rod (70) is supported, in the middle part thereof, on the pin (51) and, at the ends thereof (71), in respective seats (81) defined in the fixed part (80) of the electric motor (20); said compressor being characterized by the fact that: the clamping rod (70) extends through free spaces (33) arranged in the fixed part (80) of the electric motor (20), longitudinally aligned with spaces (34) defined between adjacent coils (31); and the ends (71) of the clamping rod (70) are housed in the seats (81) by the inner sides (82) thereof. 2. Refrigeration compressor, according to claim 1, characterized in that the seats (81) are defined by projections (92), diametrically opposed to each other, which extend radially outwards from an outer surface (91) of a protective cover (90) of the electric motor (20). 3. Refrigeration compressor, according to claim 2, characterized in that the length of the clamping rod (70) is completely arranged inside the circumference defined by the protective cover (90) and the projections (92) Of the same. Refrigeration compressor according to claim 2, characterized in that the protective cover (90) is polymeric and is made by injection molding. 5. Refrigeration compressor, according to claim 2, characterized in that the projections (92) are formed by at least two adjacent and opposite halves.